Next open each post on your main blog page, make one minor change such as adding a space and then deleting it, and then click "update post. WordPress should automatically correct any HTML issues in the posts and fix the issue.

If that doesn't do it, then you are going to have to slog through all your text widgets in the sidebar and look for bad code or missing tags.

You need to go through all your posts in the HTML tab and see if there are other such instances.

You also need to do something with that table that is hidden below the sidebar. What good is having it in there if people cannot read what is hidden?

One thing you can do is set your blog to show only one post per page (settings > reading) and then go through all the posts in IE using the previous post link at the bottom of the page to see which posts break the blog.